The First Doctor, Ian Chesterton, Barbara Wright and Susan briefly suffered from amnesia after the TARDIS' fast return switch got stuck, which would have sent it back to the creation of a solar system and resulted in its destruction. The ship crashed itself in an attempt to warn its passengers of the dangers, and a small explosion occurred in the TARDIS as the Doctor tried to correct its faulty navigation circuits, rendering all four unconscious. (TV: The Edge of Destruction)

The Time Scaphe crew lost their memories after their ship collided with the TARDIS, but regained them after Ace told them the name of their home world, Gallifrey. The TARDIS took the Doctor's memories to keep them safe from the Process, but later returned them to save itself from destruction. (PROSE: Cat's Cradle: Time's Crucible)

The Seventh Doctor and the people who had consumed the essence of the Celestial Toymaker gave themselves electroshock therapy to suppress their memories of him in an attempt to destroy him. (PROSE: The Magic Mousetrap)

The Seventh Doctor briefly suffered from amnesia when he was thawed out after being frozen in ice for millions of years. (AUDIO: Frozen Time)

The Master suffered from amnesia while on Perfugium as the Doctor's deal with Death caused him to revert to the persona he would have been if Death had not marked him as her champion. (AUDIO: Master)

The Eighth Doctor suffered from amnesia after falling into the Master's trap, requiring him to be guided by Rassilon to regain his memories by visiting and mentally linking with his previous seven selves. (PROSE: The Eight Doctors)

The Panjistri supplied the Kirithons with zavát which, in addition to being their main food source, weakened their resistance to telepathic suggestion, allowing the Panjistri to suppress certain memories and even the Kirithons' awareness that they should have those memories in the first place. (PROSE: Timewyrm: Apocalypse)